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Curtain Capability Tokens

The Curtain is the mechanism that lets Syn_OS ship the same code to a 14-year-old playing GRIMOIRE and to a federal contractor running offensive operations under a customer agreement, without those two systems being interchangeable.

It evolved across three generations:

  • Curtain v1 — build-time ELF symbol scanner + feature audit + lab integrity manifests. Static.
  • Curtain v2 — runtime capability ceiling with seven enforcement points (tier gate + seccomp + AppArmor + taint + prompt guard + syscall filter + mesh).
  • Curtain v3 (v54 Sundered Crown — current) — tier-based ed25519 capability tokens, signed and chained, enforced by an LSM hook in synos-security.

Why Curtain exists

Section titled “Why Curtain exists”

GRIMOIRE Public is the talent funnel. The premise is that play produces operators. But play is only valuable if the platform under the play stays educational — if a sufficiently determined player could compile their way out of the public profile and end up with full ALFRED Master mode and the offensive C2 toolchain, the platform would be a vulnerability vendor disguised as a school.

Curtain enforces, by construction:

  • Public players cannot enable AI dispatch syscalls (470–474 return ENOSYS no matter what)
  • Public Sanctums cannot federate with Master Sanctums
  • Public audit trails use a separate HMAC-SHA256 chain root from Master
  • Fragment Field IDS kernel-side detection is Master-only (public gets userspace-only access)
  • C2 framework binaries are scrubbed at build time on the public profile

These rules are not enforced by best-effort runtime checks. They are enforced by a refusal to issue, sign, or accept the capability tokens that would allow them.

Token format

Section titled “Token format”

A Curtain v3 capability token is an ed25519-signed envelope containing:

{
  "version":   3,
  "issuer":    "<sanctum-fqdn>",
  "tenant":    "<tenant-uuid>",
  "tier":      "grimoire-public" | "goodlife" | "master",
  "subject":   "<process-or-node-uuid>",
  "claims":    [ "syscall:475", "ebpf:enable", "federation:peer" ],
  "issued":    1746813600,
  "expires":   1746900000,
  "nonce":     "<32-byte hex>",
  "parent":    "<token-id>",
  "algorithm": "ed25519"
}

…with a signature appended. Tokens are short-lived (typically ≤24 h) and chained: each token references the parent that authorised its issuance, all the way back to the federation root.

The algorithm field is forward-compatible with ML-DSA for the planned post-quantum migration.

Tiers

Section titled “Tiers”
TierIssued byAuthorised claims
grimoire-publicGRIMOIRE federation rootXP-bounded tool unlocks, lab launch, GRIMOIRE-tier mesh peering
goodlifeGoodLife federation rootResearch-mode AI primitives, no offensive tools, no Master peering
masterMaster federation rootAll claims; gated by a customer agreement and a hardware attestation

There is no “elevate” claim. A grimoire-public subject cannot acquire a master token under any in-band path — the issuance ceremony for a master root requires a hardware-attested ceremony with two custodians, and the federation root’s signing key never leaves an offline HSM.

The seven enforcement points (v2, still active under v3)

Section titled “The seven enforcement points (v2, still active under v3)”

Curtain v3 inherits and augments the seven runtime enforcement points from v2:

  1. Tier gate — token tier checked on every privileged operation (LSM hook in synos-security)
  2. seccomp BPF — 18-syscall deny list enforced per-process for lab sandboxes
  3. AppArmor — synos.grimoire.lab profile pins file access
  4. Kernel taint flag — once set (e.g. an unsigned module loaded), the process loses Master claims permanently
  5. PromptGuard — content guard between user prompts and ALFRED’s master-mode actions; signed receipts in synos-attest-ledger
  6. Syscall filter — direct dispatch table check for 469–485 (return ENOSYS based on tier)
  7. Mesh peering — federation handshake refuses cross-tier sessions

Issuance flow

Section titled “Issuance flow”
1. Subject requests a token from its local Sanctum:
   POST /v3/curtain/request
   { tier: "grimoire-public", claims: [...], duration: 3600 }


2. Sanctum verifies the requesting subject (mTLS + tenant scope).


3. Sanctum consults policy (Riftrunner-VM bytecode, hot-loadable):
   - Is this claim allowed for this tier on this tenant?
   - Does the requesting subject have an unexpired parent token?
   - Are XP / progression gates satisfied (GRIMOIRE)?


4. If approved:
   a. Build the token envelope (see above).
   b. Sign with the tenant-scoped ed25519 key.
   c. Append issuance to `synos-attest-ledger` (HMAC-SHA256 chain).
   d. Return the token to the subject.


5. Subject presents the token on every gated operation.
   The LSM hook verifies the signature, checks the chain, enforces.

Revocation

Section titled “Revocation”

Tokens are short-lived by default (1–24 h). For longer-lived claims, the Sanctum maintains a per-tenant revocation list that the LSM hook consults on every operation. Revocation propagates through Sanctum federation gossip in seconds.

Mass revocation (e.g. a lost laptop, an incident response action) is an Ansible playbook (ansible-playbook revoke-tenant.yml --extra-vars "subject=<uuid>").

Receipts and attestation (v46 Threadwalker)

Section titled “Receipts and attestation (v46 Threadwalker)”

Every Curtain decision produces a PromptGuard receipt chained into synos-attest-ledger:

  • Decision (grant / deny)
  • Subject identity
  • Claim requested
  • Policy hash
  • Timestamp
  • HMAC-SHA256 chain link

The ledger is append-only, replicated across Sanctum federation peers, and signed at epoch roots with SLH-DSA. Audit pulls it for SOC2 / CMMC / FedRAMP evidence.

Why this matters commercially

Section titled “Why this matters commercially”

The Curtain is the bedrock of the LumOs commercial model. GRIMOIRE Public is the talent funnel that produces the best cybersecurity operators in the world; Master is the product LumOs sells to customers who need the actual weapon for actual work. Both are built from the same codebase, audited together, and shipped by the same supply chain — but Curtain v3 makes the boundary between them mechanical, signed, and externally auditable.

Section titled “Related”